1. Technical Field
The present disclosure relates to an image sensor and a method of manufacturing the same.
2. Description of the Related Art
Image sensors may convert optical images into electric signals. In recent years, with the development of computer industry and communication industry, the demand for image sensors with advanced performance has increased in various fields, such as digital cameras, camcorders, PCSs (personal communication systems), game machines, security cameras, and medical micro cameras.
In particular, metal oxide semiconductors (MOS) image sensors may be easy to operate and may be implemented by various scanning methods. In addition, a signal processing circuit provided therein may be integrated into a single chip, which makes it possible to reduce the size of the MOS image sensors. Further, the MOS image sensor can be manufactured by MOS technology, which may lower the manufacturing cost. The MOS image sensor may have low power consumption, and may be used in products having limited battery capacity. Therefore, the development of the MOS image sensor makes it possible to improve the resolution. For at least the above reasons, the demand for the image sensor has rapidly increased.
The MOS image sensor may be divided into a sensor array region having a plurality of unit pixels formed therein and a peripheral circuit region having circuits for controlling/driving the plurality of unit pixels formed therein. The sensor array region may include photoelectric conversion elements and a plurality of MOS transistors, and the peripheral circuit region may include a plurality of MOS transistors. The sensor array region and the peripheral circuit region may be integrated into one substrate, and the MOS transistors in the sensor array region and the peripheral circuit region may be formed at the same time.
Recently, with an increase in the number of wiring layers in the peripheral circuit region, the difference between the number of wiring layers in the sensor array region and the number of wiring layers in the peripheral circuit region has also increased. For example, four or more wiring layers may be formed in the sensor array region, and two or more wiring layers may be formed in the peripheral circuit region. Even though two wiring layers are formed in the sensor array region, four or more interlayer insulating films may be formed in the sensor array region. When a thick film is formed on the photoelectric conversion element, the intensity of light incident on the photoelectric conversion element may be lowered, which may deteriorate various optical characteristics.